This Program Project proposes an interactive multidisciplinary program of research into the genetics, molecular pharmacology, immunology and experimental therapy of the malignancies of the developing nerve, bone and muscle affecting children. The overall objective is: the identification, functional analysis and targeted therapeutic modification of genes and gene products uniquely or differentially expressed by the developmental malignancies of childhood. The Program Project has 4 research projects and 5 cores. Project I proposes to identify distinctive signatures of gene expression that define therapeutically relevant subclasses of these developmental tumors and to identify genes and pathways that provide potential targets for drug and immune-based therapy by virtue of their differential expression or altered function. Project II proposes to evaluate the function of the unique fusion genes that characterize Ewing's sarcoma, alveolar rhabdomyosarcoma and desmoplaslic small round cell tumor (DSRCT), to identify their targets and to characterize the alterations in gene expression and tumor cell function associated with their inhibition. Project IV proposes to evaluate novel ScFv streptavidin conjugate-based strategies for delivering radioconjugates, cytokines or effector cells to tumors to enhance tumor targeted activity and to reduce toxicities currently associated with non-specific uptake of native antibodies or antibody conjugates in organs such as the liver or the kidneys. Project V proposes to evaluate the anti-tumor activity of T lymphocytes generated from the blood of tumor bearing and normal hosts by sensitization with peptides derived from oncofetal proteins differentially expressed by developmental tumors of childhood. Practicable strategies will also be developed for generating T cells specific for peptides derived from these oncofetal proteins from patients not sharing common HLA alleles. The anti-tumor activity of T cells specific for novel epitopes will be compared with that of T cells generated against known immunogenic tumor peptides, as will be their capacity to home to and induce regressions of tumors in xenografted mice. Based on these studies, a phase I trial evaluating T cells specific for WT1 peptides in the treatment of WT1 malignancies of childhood will be conducted. The Program Project also includes 5 cores, a Pathology Core for evaluation of clinically annotated specimens, a Clinical Core to ensure appropriate accrual and careful evaluation of uniformly treated patients afflicted with these developmental tumors, a Preclinical Testing Core to assess and validate the activity of agents targeting genes or gene pathways found to be differentially expressed in specific developmental tumors against well-characterized tumor cell lines and, as appropriate, patient derived tumor cell populations both in vitro and in NOD/SClD xenograft models, a Biostatistics Core to guide the design of experiments in in vitro and in vivo models and to provide relational bioinformatic support for analyses of patterns of gene expression and an Administrative Core to enhance communication, prioritize efforts and provide appropriate scientific interchange and oversight.